Use of Coatings to Protect Steels Against Lead Corrosion at High Temperatures

New techniques in reactor technology favour the use of liquid lead on account of its advantageous physical and thermal qualities as heat carrier. Although the solubility of iron in pure liquid lead is low the corrosion action of lead in chemical processes limits the exposure time of the steels employed. Thus in lead bath patenting the containers must be repaired or even renewed every two years. Furthermore attack of the metal containers can be observed in lead ladles in which temperatures up to 1000 K are used for hardening and tempering. The use of other base metals is generally impossible because of prohibitive prices, low strength at elevated temperatures or poor workability. As an alternative it is possible to coat high temperature steels with suitable materials which are corrosion resistant against lead and adhere sufficiently to base metals.